Electrical protective device



Oct. 3, 1933.

A. J. MOTTLAU ELECTRICAL PROTECTIVE DEVICE Filed May 15, 1929 3 Sheets-Sheet l IN\ ENTOR Oct. 3, A J MOTTLAU ELECTRICAL PROTECTIVE DEVICE Filed May 15, 1929 3 heets-Sheet 2 INVENTOR Patented Oct. 3, 1933 UNITED STATES PATENT OFFICE 20 Claims.

My invention relates to electrical protective devices for electric circuits and for translating apparatus connected thereto.

The primary object of my invention is to provide an automatic switching device for protecting a supply circuit against excessive overload in a connected loadcircuit, by automatically disconmeeting the load circuit from the supply circuit, subsequently reconnecting the'two circuits and automatically repeating the disconnection and reconnection of the two circuits a predetermined number of times as long as the overload condition exists in the load circuit, and then permanently disconnecting the two circuits, if the abnormal load condition continues; but that shall be operative to reestablish itself for a subsequent control cycle, if the overload conditions are transient and disappear before the two circuits are permanently disconnected.

A further object of my invention is to provide a control device of the foregoing character that shall be adjustable to permit the reconnection of the circuit a predetermined number of times before permanently disconnecting them, if the abnormal condition should be a permanent one.

Another object of my invention is to provide a simple device for counting the number of operations of the switch mechanism'which connects and disconnects the two circuits, and for locking the switching mechanism against further operation, or for resetting itself at its initial position to be subsequently effective throughout its entire predetermined cycle of control if necessary.

A further object of my invention is to provide a counting device of the foregoing character that shall be simple and reliable in its construction andoperation, and that shall be readily adaptable with but simple modifications to actuating mechanism and switches of different types and sizes.

In many applications where motor-operated devices are employed, as, for example, in domestic refrigerators or in washing machines, or in machine shop tools, the motor is provided with a protective device for disconnecting it from its supply circuit upon the occurrenceof abnormal load conditions imposed upon it by the device or machine that it is operating.

In automatic apparatus such as domestic refrigerators, an operation of the protective device of the types 'at present used, disconnects the motor from its supply circuit. The automatic control equipment usually associated with the refrigerator motor for controlling the motor to establish and maintain a desired temperature condition, is thereupon rendered Before any indication is given that the protective equipment has operated due to the occurrence of an abnormal condition, an undesirable high temperature is permitted to establish itself in the refrigerator.

The abnormal condition might have been one of a continuing character or it might have been of a transient character. Where the abnormal condition is of a continuing character, it is of course desired that the protective equipment operate to disconnect the motor from the supply circuit until the faulty condition may be rectified.

When the abnormal condition is of a transient nature, however, it is obviously undesirable to permanently open the motor circuit upon the occurrence of such condition, since there is nothing to be manually rectified later and the advantage of the automatic control equipment for maintaining the predetermined temperature has been lost in the meantime. Up to the present time, so far as I am aware, there has been nothing available, or offered, to the public that would serve as a protective device and at the same time would distinguish between faults or abnormal conditions of a continuing nature and those of a transient nature.

The control device described herein and embodying the principles of my invention functions as an automatic protective device to disconnect a motor from its supply circuit upon the occurrence of abnormal conditions. After a short interval of time, however, the device operates to reconnect the motor to the supply circuit. If the abnormal condition which caused the first disconnection of the motor from the circuit still exists, the device will operate again to disconnect the motor from the circuit. Of course, if the abnormal condition has passed, the motor circuit connection to the supply circuit will remain es tablished and the motor will continue to operate subject to the control of the temperature control equipment.

Let us assume, for example, that the faulty condition has continued through the second opening of the motor circuit. After a short interval of time, the motor circuit will be again re-estab lished. If the abnormal condition still continues, the motor circuit will again be automatically opened and be permanently held open until manually reset by the person who rectifies the existing faulty condition. If, however, before such second reclosure, the abnormal condition has passed, the motor circuit will remain established, subject to the control of the temperature control inffective.

equipment. At the same time the counting device will automatically reset itself for a subsequent operation to permit its control or" the motor circuit according to the predetermined cycle for which the counting device is set.

The counting device may be adjusted to permit any desired number of successive reclosures of the motor circuit before permanently holding it open, and will automatically reset itself to its initial control position if the abnormal condition clears itself before the final reclosing operation permitted by the counting device.

In the refrigerator application just described, the operation of the protective device is entirely independent of the operation of the automatic control equipment for maintaining the desired temperature. The temperature control equipment might be functioning to cause the motor to operate to maintain such temperature, but the protective device described herein would assume control, if the abnormal'condition occurred while the temperature control was functioning.

I have described the operation of the protective device herein with respect to a refrigerator since a refrigerator is intended to be automatic in its operation and normally has no manual attendant. It is, of course, obvious, that such an automatically resetting device is particularly desirable for such an application. It provides the same utility, however, where the motor operated device is attended, since under such circumstances the abnormal condition might be in the nature of a transient one if it was caused by the attendant and can be immediately rectified. the abnormal condition is not one that was caused by the attendant and cannot be immediately rectified, the protective device will disconnect the driving motor from its supply circuit after the protective device has operated through its cycle of reclosure and has found that the faulty condition is a continuing one.

A controlling device of the foregoing character, embodying the principles of my invention is described herein in connection with the accompanying drawings, in which Figure 1 is a front elevational view of the control device mounted as a unit upon a panel together with the circuit connections showing the disposition of the device in the electric circuit with which it is to be employed;

Figure 2 is a side elevational view of the counting device which determines the number of reclosures of the main motor circuit that are to be permitted, and

Figure 3 is an end view of the counting device in Fig. 2;

Figure 4 is a plan view of the counting device in Fig. 2;

Figure 5 is a vertical sectional view of the counting device taken along the line V-V in Fig. 2;

Figure 6 is a plan View of the switch mechanism;

Figure 7 is a side sectional view of the switch in -1 open position;

Figure 8 is a similar view of the switch in closed position;

Figure 9 is a front elevational view of the switch;

Figure 10 is a plan view of the double lever arm arrangement for controlling the switch; and

Figure 11 is a front elevational view of the lever arms in Figure 10.

As is illustrated in Figure 1, a system in which the protective device may be employed comprises a supply circuit 1, and a load circuit 2 to which is connected a motor 3 that is to be protected against overload by a protective device 4. A switch 5 is shown in series with the motor and protective device to permit complete isolation of the motor or the protective device from the supply circuit when it is desired to work upon either of them.

The protective device 4 comprises, in general, a switch 6, an actuating element 7, and a counting device 8 for controlling the number of times that the actuating element '7 may operate the switch 6 under predetermined load conditions.

The switch 6 and the energizing coil for the actuating element 7 are connected in series with the motor circuit 2. The actuating element is thus energized in accordance with the current to the motor, and opening of the switch 6 disconnects both the actuating element and the motor from the supply circuit 1.

In the modification illustrated herein the actuating element 7 comprises a hollow tubular body 10, open at one end and closed at the other end by an expansible member such as a bellows 12. At the open end of the tubular body 10 is disposed a tubular recessed cup 13 of insulating material upon which is mounted an electrical conductor or heating element 14. The open end of the tubular element 10 is provided with an internal flange or shoulder 15, having on its outer surface a circular ridge 16 of triangular cross section. The end surface of the insulating cup 13 is provided with a depression 1'7 of corresponding triangular shape which co-operates with the ridge 16 to hold packing ring 18 to provide a tight seal. The insulating cup 13 and the tubular body 10 are clamped together tightly by a threaded clamping ring 19 provided with an internal flange 20, for engaging a shoulder 21 of the insulating cup 13, and with a threaded portion 22 for threading onto a threaded portion 23 of the tubular element 10.

During assembly the unit is completely filled with carbon-tetrachloride which has a relatively large coefficient of thermal expansion. When current traverses the conductor or heating element 14 the carbon-tetrachloride is heated and expands in volume and causes expansion of the bellows element 12.

Although I have illustrated a thermally responsive actuating element, I desire it to be understood that it is representative of, and equivalent to, any actuating device whose movement is a function of the energizing current. In recent years, the thermal principle has been adopted generally for protective purposes and in protective devices because it permits a better approximation of a thermal condition corresponding to that developed in the apparatus to be protected, under varying load conditions.

For that reason I prefer to employ, in the protective device, a thermally-responsive actuating element having a relatively large thermal mass or thermal storage capacity, in order to approximate more closely the conditions of relatively large thermal capacity in the apparatus to be protected. The thermal actuating element is designed to function in response to a temperature developed therein that shall be sufficiently above ambient temperature to be relatively unaifected by ordinary variations in the ambient temperature.

When the heating element 14 is energized continuously by full load current the carbon-tetrachloride expands sufiiciently to expand the bellows element 12 and move the bellows head 24 to an advanced position. As long as the circuit current does not exceed full load value the bellows head will not move beyond such position. Upon the occurrence of an overload, however, the increased current traversing the heating element heats the carbon-tetrachloride sufficiently to advance the bellows head beyond its full load position and such increased movement is utilized to actuate the switch.

The switch 6 which I employ constitutes the subject matter and is fully described in my copending application, entitled Switch mechanism, Serial No. 340,670 filed Feb. 18, 1929 and will be described and referredto ina general manner here without referring specifically to the various details of construction, since such detailed description is deemed unnecessary in the present application.

The switch .6 comprises in general two stationary contact members 25 and 26, a movable bridging contact member 27 consisting of electrically connected rolling contacts 28, a supporting arm 29 for the movable contact 27, and an operating spring 30 for moving the arm 29 to effect engagement or disengagement of the stationary contact members 25 and 26. A slight biasing action is imparted to each of the stationary contactmembers 25 and 26 by helical springs 31 to cause the contact members to tend to move inwardly toward each other. Movement beyond predetermined positions is precluded however by a stop member 32. The contact members 25 and 26 move slightly toward each other, however, so that when they are engaged is supported. by two short flat resilient leaf springs 36 and 37. One end of each of these supporting leaf springs is secured to one end of the cross bar and the other end of each of these supporting springs is anchored on a suitable boss or elevation 38 of the base 39 upon which the switch is mounted.

All of the springs are riveted to their associated elements or points of support so that no wearing points are provided in the actuating mechanism itself.

The switch is so designed that under normal closing conditions, the actuating spring 30 is under compression between two ends at which it is supported, thereby establishing a bow to one side of a general center line between its ends. The amount of compression and the consequent extent of bowing of the spring are controlled by an adjusting element 40 associated with the cross piece 34.

The theory of operation of the switch is that the actuating spring 30 in assuming either bowed position'changes the angle between a tangent at either end portion and'the center line between its ends. Such change of angle is, in fact, a complete reversal insofar as it transfers the angular disposition across the plane of the center line itself. By moving the upper end'of the spring and causing the spring to bow in the opposite direction, the lower end of the spring is caused to change its angle with respect to the center through such angle is utilized tooperate the arm '29 which supports the movable contact member 27. Actuation of the spring to move the bow from one side to the other, is effected by impressing a force upon the upper cross piece 34. It will be observed upon reference to Fig. 8 that the spring 30 in the normal bowed position of the switch, when closed, is normally below the points of support of the side supporting springs 36 and 37. Movement of the upper end of the spring by means of the force impressed upon the cross bar 34 turns the upper end of the spring about the point where secured to the cross bar 34, as a center, until the spring passes beyond the anchor points at which the side supporting spring 36 is secured to the bosses 38. The bend in the spring continues to move along the spring in serpentine manner until it causes the spring to reverse its bow at its other point of support at the lower cross bar 35.

When the spring reverses its bow at the cross bar 35 the movable arm 29 which is secured to the cross bar 35 is moved about its point of support to the cross bar as a center in the manner of a pendulum and disengages the movable contact member 27 from the stationary contact members 25 and 26. By means of the switch construction here illustrated a snap-action make and break of the contact members is effected. The switch in the present application is designed to have a bias toward closed position.

The supporting side springs 36 are made shorter in length than the side springs 37. The movement of the upper end of the spring is thereby limited and confined more than the movement at the lower end of the spring. The disposition of 115 the upper end of the spring is also such in its cross bar 34 that the spring does not pass beyond the plane through the anchor point of the spring 36. Consequently when the operating force is removed from the upper end of the spring it tends 120 to restore itself to its initial position and thereby reclose the switch contacts.

It will be observed that the action and operation of the switch are essentially such that the actuating spring constitutes in effect a resilient I25 single-piece toggle. I

We come now to consideration of the counting unit 8 which controls the number of times that the switch 6 maybe operated by the actuating element 7, depending upon the circuit condition.

Actuation of the switch is effected by either of two lever arms 42 and 43, acting upon a common saddle 44 that is pivotally supported on a pin 45 passing through both lever arms 42 and 43, intermediate therein. Each lever arm 42 and 43 is provided with a bifurcated end which pivotally straddles a slotted section of a pin 47. The other end of each lever arm is provided with a rounded head 48. Upward movement of the head 48 of either lever arm will operate the spring to cause the switch to open. Unimpeded return movement of both lever arms will permit the spring to cause the switch to reclose.

The counting unit 8 comprises in general a push rod 50, a supporting frame 51, two guide bearings 52 and 53 for the push rod 50, a pawl and ratchet counter 54, alatch 55, a manually operable reset cam 56 provided with a lever 5'7, 150

and a combination detent and. automatic reset element 58.

When the thermal actuating element '7 is not energized the push rod 50 occupies its normal retarded position as shown in full line in Fig. 2, being biased thereto by a compression spring 60 that is disposed between a stop pin 61 and the end surface of a slot 62 in the push rod 50. The push rod .50 is illustrated as being of square cross section. A square flange or shoulder stop 64 that is disposed on the forward end of the push rod 50 determines the extent of backward movement of the stop or the initial position to which it may be biased or moved by the spring 60, when the flange or shoulder 64 engages the outer forward surface of the guide 53. The forward movement of the push rod 50 is determined and limited by a vertical bracket 66 in case the rod should be pushed forward sufliciently to cause the bracket 66 to engage the rear outer surface of the guide 52. Normally, however, such limiting action is unnecessary since the switch will be open before the engagement of such surfaces and the opening of the switch will also open the circuit of the heating coil in the thermal actuating element '7, thereby preventing further energization thereof.

As will be observed upon reference to Fig. 1, there is a certain amount of space between the lower end of the push rod 50 and the head of the expansible bellows. As the actuating element becomes heated the bellows head moves forward to engage the end of the push rod and, at a position corresponding to sustained full load, the

push rod will be moved forward to a position indicated by the dotted line in Fig. 2. It will be seen that at this point the pawl 54a engages the surface 6'7 of the first tooth of the counting ratchet associated therewith.

Under normal non-energized conditions, the counting ratchet is biased to a retarded position by a helical spring 69 anchored at the point '70 to the supporting frame 51.

The ratchet element 68 is of substantially channel shape and is provided with a base '71, and two side faces '72 and '73. The side face '72 constitutes the actuating ratchet face and is provided with a number of teeth, depending upon the number of times that it is desired to permit the switch to be reclosed before it is permanently locked out. The lower side surface '73 is also provided with teeth whereby the detent 58 may operate to retain the counting ratchet in the foremost position to which it has been actuated, until it is released. The latch is pivotally supported on the base of the ratchet element by a pin '74 just below and within the ratchet face '72.

When the circuit current exceeds full load value the actuating element 7 is increasingly energized to cause the push rod 50 to move forward to an advanced position to open the switch after a time interval that is in general an inverse function of the load current traversing the circuit. 7

The push rod 50 in moving forward to actuate the switch, moves the pawl 54a and the ratchet -68 forward through a corresponding distance,

which in the present unit, described herein, has been designed to correspond to the tooth pitch or spacing between teeth, on the ratchet and on the detent of the element.

When the ratchet is moved forward the dis tance of one tooth, the detent 58 engages the tooth surface '75 of the lower portion '73 of the ratchet member, to prevent the ratchet member from returning to its original position.

It will be observed that, when the push rod 50 is in an advanced position corresponding to 100% full load, or more, an automatic reset arm '76, on the lower end of the pawl-supporting bracket 66 will also be advanced sufiiciently to permit the detent member 58 to be moved upwardly by a biasing spring '77 when the position of the lower ratchet surface 73 permits.

' The reset arm '76 carries a small roller '78, that cooperates with a release arm '79 on the detent member 58 to move the detent 58 out of engagement with the lower ratchet section '73 when the unit is to be automatically reset. In the forward movement of the push rod 50 the roller 78 passes over the incline surface at the end of the reset arm '79 and moves the detent 58 out of engagement with the ratchet section 73 but there is no tendency for the ratchet to restore itself or to move backward since it is already in its maximum backward or initial position.

When the push rod 50 is moved forward and the pawl 54a engages and advances the ratchet 68, the front edge of the pawl is lifted somewhat to permit such movement, and in order to return the pawl to its initial position after each operation, the pawl is pivotally supported on the bracket 66 by means of a pin 80 and is provided with a cam shaped back 81 which is engaged by a biasing spring 82, secured to the bracket 66, to bias the pawl to its downward initial position. A stop 83 on the lower part of the pawl engages the forward surface of the supporting bracket 66 and limits the downward movement of the pawl to the predetermined necessary amount.

Assuming a first occurrence of an overload condition, the push rod 50 is moved forward by the thermal actuating element '7 and operates the switch 6 to open the load circuit. At the same time pawl 54a moves the ratchet element 68 forward the space of one tooth, at which position the detent 58 engages the lower section '73 and maintains the ratchet in that position.

The switch having operated to open the load circuit, the actuating thermal element '7 is now de-energized and gradually dissipates the heat stored therein to the surrounding air. As the thermal element cools, the volume of the enclosed carbon-tetrachloride diminishes and the expansible bellows element tends to resume its initial position, or, at least, to move backwards toward its initial position. The adjustments between the switch, the push-rod and the thermal actuating element are such that the switch will reclose automatically before the push rod is returned to the position corresponding to full load, as indicated by the dotted lines in Fig. 2, under the influence of the biasing spring 62.

Upon reclosure of the switch the subsequent action of the entire unit is controlled by the conditions in the load circuit. load condition has been a transient condition and has disappeared 'before the reclosure of the switch, the thermal actuating element will be energized to a degree less than full load and will return to a position that will permit the push rod 50 also to move back towards, or to, its initial position. When the push rod 50 returns past the Fl 0% load position, the automatic reset arm '76 and its roller '78 engage the auxiliary reset '79 on the detent 58 and force it downward against the action of the biasing spring 7'7 to release the ratchet section '73. The entire ratchet element thereupon is restored to its initial position under the influence of the biasing spring 69.

The device is now automatically reset to its If the abnormal initial position and is ready to function throughout an entire cycle for which it is adjusted.

Let us assume that the abnormal condition which caused the first opening of the switch is a continuing one and exists after the switch has been automatically reclosed. The actuating element '7 will be immediately re-energized, and, instead of moving toward its normal cold position, will again be caused to move the bellows head against the push rod 50. Since the switch closed before the push rod returned far enough to cause the automatic release arm '76 and the auxiliary arm 79 to engage and release the detent 58, the detent 58 will remain in position and hold the ratchet in its first advanced position corresponding to one automatic opening of the switch. After a short timeinterval the actuating element again pushes the push rod forward sufiiciently to re-open the switch and at the same time advances the pawl and ratchet mechanism another step to a second advanced position, at which the ratchet unit is held in place by the detent 58.

With the second opening of the switch, the

I thermal unit '7 is de-energized and again moves toward its initial de-energized position and permits the switch to reclose again just before the thermal unit has movedback as far as its 100% full load position.

The further operation of the protective device is again determined by conditions that now exist in the load circuit. If the abnormal condition has been corrected before the switch has reclosed, so that the load current is less than, or at least i does not exceed full load value, the push rod 50 will move back sufficiently to cause the automatic the front guide 53.

reset arm 76 to engage the auxiliary reset portion 79 and release the detent 58. If on the other hand the abnormal condition still exists so that the thermal element is again energized by current in excess of full load, the thermal element will again actuate the push rod and cause it to open the switch.

Assuming that the pawl and ratchet unit has ibeen adjusted to permit three openings or the switch or two. reclosures, the movement of the ratchet element 68 to its third advanced position will be suflicient to move the latch 55 far enough to permit it to drop beyond the front edge of The latch member 55 now servesas a stop to prevent the limiting flange or shoulder64on the push rod 50 from returning to its initial position against the front surface of the guide 53 and thereby prevents reclosure of the .The switch is now locked in open position by the latch 55 and maintains the load and the sup,- ply circuits disconnected until an attendant may rectify the abnormal condition in the load circuit and then manually reset the switch.

To reset the switch and restore the protective unit to its initial operating position the handle 57 of the reset cam 56 is rotated toward the lefthand side as viewed in Fig. 2 and the cam 56 raises the latch 55 to permit the biasing spring 62 to restore the push rod 50.to its initial position. When the reset lever 5'7 is releasedit is moved back to its initial position by a biasing spring 85 acting upon a lower depending portion 86 of the reset cam 56. The cam is thereby returned to its initial position atwhich it is out of the way of the latch 55 therebypermittingthe latter to drop in position if conditions so require.

When the latch is withdrawn and the push rod 50 is permitted to resume its initial position, the

automatic reset arm '76, by means of the roller '18 acting upon the auxiliary arm '19, disengages the detent 58 and permits the ratchet counting unit to resume its initial position for the beginning of the cycle. 1 A

Although I have illustrated the device as operaive to permit three openings of the switch it is obvious that any number of operations may be provided for by employing a corresponding number of teeth.

In order to provide for a different number of operations of the same device when applied in different applications, the ratchet base may be provided with the maximum number of teeth corresponding to the maximum number of operations that may be desired and then adjusted, as by means of a stop 88, to advance the position of the ratchet at its maximum retarded position. Such adjustment is obtained by moving a stop member 88 underneath the end of the ratchet face '72 and should be of sufficient width to raise the base one tooth or two teeth according to the schedule of operations desired of the counting unit for that particular application.

By means of a control protective device of the character described electrical translating apparatus may be protected against overload and at the same time automatically controlled according to the continuing or transient nature of the abnormay condition that caused the first operation of the protective element.

Although I have illustrated the principle of scheduled condition as applied to an electrical protective device, I desire it to be understood that it may with equal benefit and utility be utilized in connection with any control device in which a predetermined condition establishes an undesired effect which might be either of a continuing or of a transient nature. Moreover, although I have illustrated the invention in a protective device in which the actuating unit is thermally actuated or thermally energized, it will be obvious to those skilled in the art that the principle of the invention is entirely independent of the nature of the actuating element, which may be electro-magnetically or mechanically operated by any suitable medium.

My invention is therefore not limited to the particular construction or features of design that are illustrated herein but may be variously modified and applied to other control devices and other applications without departing from the spirit and scope of the invention as set forth in the appendant claims.

I claim as my invention:

1. A thermal protective device for an electric circuit comprising a thermally responsive element to be energized from the circuit, a. switch mechanism controlled thereby to control the circuit, and

means associated with the thermal element and the switch mechanism for permitting only a pre- H determined number of resetting operations of the switch mechanism during overload conditions in the circuit.

2. A thermal protective device for an electric 3. A thermal protective device for anelectric l circuit comprising a thermally responsive element, to be energized from the circuit, a switch mechanism controlled thereby to control the circuit, and a pre-set counting device operatively associated with the thermal element and-the switch mechanism for controlling the actuation of the switch mechanism to permit a predetermined number of resetting operations of the switch during a sustained overload condition in the circuit.

4. ,A thermal protective device for an electric circuit comprising a thermally responsive element to be energized from the circuit, a switch mechanism for the circuit, and means controlled by the thermal element to actuate the switch and to permit the switch to reset a predetermined numberof times during a sustained overload condition in the circuit, and operative to then look the mechanism against further operation during such overload condition.

5. A thermal protective device for an electric circuit, comprising a thermally responsive element to be energized from the circuit, a switch mechanism controlled thereby to control the circuit, and automatic self-resetting means controlled by the thermal element for permitting the switch to reset a predetermined number of times during a sustained overload condition in the circuit.

6. A thermal protective device for an electric circuit, comprising a thermally responsive element to be energized from the circuit, a switch mechanism to be actuated thereby to control the circuit, an associated counting device actuable by the thermal element to control the resetting of the switch, and means associated with the counting device for pre-setting it to determine the number of resetting operations to bepermitted by the switch under predetermined load conditions in the circuit.

'7. A thermal protective device for an electric circuit comprising a thermally responsive element to be energized from the circuit, a switch mechanism actuable by the thermal element, and means controlled by the thermal element for controlling the number of actuations of the switch during a predetermined load condition, said means comprising a counting element and means for pre-setting the counting element to permit a desired number of operations of the switch. a

8. An overload protective device comprising a 'load-current-responsive actuating element, a

switch controlled thereby, and a counting device responsive to the actuating element for controlling the actuation of the switch by the currentresponsive element.

9. An overload protective device comprising a load-current-responsive actuating element having a time interval in its operation, a switch actuable thereby when the actuating element is energized beyond a predetermined degree, and means responsive to the current-actuating element for permitting a predetermined number of actuations of the switch in accordance with a predetermined schedule, depending upon the degree of energization of the actuating element.

10. A protective device for an electric circuit comprising a switch, an actuating element therefor adapted to be energized by the circuit current,

manually resetting said precluding means, or for automatically resetting said means under certain conditions to permit further operation of the device.

11. A protective device for an electric circuit comprising a switch, an actuating element therefor responsive to a condition of the circuit, a counting device cumulatively responsive to actuating movements of the actuating element, means responsive to predetermined actuation of the counting device for automatically precluding turther operation of the switch and means responsive to restoring movement of the actuating element for automatically resetting the precluding means.

12. A protective device for an electric circuit comprising a switch, an actuating element therefor to be energized from the circuit, a counting device cumulatively responsive to actuating movements of the actuating element, means responsive to predetermined actuation of the counting device for automatically precluding further operation of the switch and means responsive to restoring movement of the actuating element for automatically resetting the counting device.

13. A protective device for an electric circuit comprising a switch, an actuating element therefor. to be energized from the circuit, a counting device cumulatively responsive to actuating movements of the actuating element, means responsive to predetermined actuation of the counting device for automatically precluding further operation of the switch and means responsive to restoring movement of the actuating element for automatically resetting the counting device and the precluding means.

14. A protective device for an electric circuit comprising a switch for the circuit, an actuating element for the switch capable of advance movement beyond a predetermined position to actuate the switch, and a counting device responsive to movement of the actuating element beyond such predetermined position and operative to permit only a certain number of actuations of the switch in a definite cycle while the actuating element is in its advanced position but to rest its control to permit subsequent operation through the entire cycle if the actuating element recedes to said predetermined position before operation through the first cycle is completed.

15. In an overload protective device, the combination with an actuating element, and a switch element actuable thereby to control a circuit to be protected, of means for controlling the switch actuation through a predetermined schedule depending upon the movement of the actuating element, said means comprising a spring-biased self-returning pusher rod for transmitting the force from the actuating element to the switch, a spring-biased ratchet counter actuated by the pusher rod during its forward movement, a detent for holding the ratchet counter against the returning force of its spring, means dependent upon return movement of the pusher rod to predetermined position for moving the detent to release the ratchet counter, and means for preventing return movement of the actuating rod after a predetermined number of actuations while the detent has remained effective.

16. In an electric circuit, a protective device for controlling the energization of a translating apparatus from the circuit under abnormal conditions comprising a current-responsive element, a switch element actuable thereby for controlling the connection of the apparatus to the circuit, means controlled by the current-responsive elemerit for permitting the switch to reclose a predetermined number of times through a predetermined cycle and for preventing reclosures beyond such number during a sustained overload, and means responsive to the current-responsive element for resetting said reclosure-permitting means to its initial position in the control cycle upon removal of the overload before the entire control cycle is completed.

17. A protective device for an electric circuit, comprising a switch between the circuits, means for closing the switch, means responsive to the current transferred by the switch for opening the switch upon occurrence of predetermined overload conditions, counting means for permitting a predetermined number of reclosures of the switch after an automatic opening by the current-responsive means due to overload conditions, and for precluding further reclosures if the overload conditions have not subsided, and means responsive to load conditions for automatically resetting the counting means if the load conditions became normal before the last opening of the switch in the predetermined cycle.

18. A protective device for an electric circuit, comprising a switch, an actuating element responsive to the current transversing the switch and the motor for opening the switch, and counting means responsive to the actuating element when the latter is energized in excess of full load, and operative to permit only a predetermined number of reclosures of the switch if the circuit conditions are such as to energize the actuating element beyond full load upon each reclosure, but operative to reset itself to an initial position if the energization of the actuating element is less than full load after any actuation prior to the last of said predetermined number.

19. A control device comprising a control contact member and a counting mechanism for controlling the operation of the contact member in accordance with an external condition to be controlled, said counting mechanism comprising a reciprocating push rod, means biasing the rod to an initial starting position, a ratchet member and means biasing it to an initial position, a pawl actuable by the push rod to advance the ratchet member to an advanced position, a detent biased to hold the ratchet member in any maximum advanced position to which it may be moved by the pawl under certain conditions, means responsive to a predetermined advance movement of the ratchet for looking it against return by its biasing means, and means responsive to a predetermined return movement of the push rod, before the ratchet member has been locked, for moving the detent to release the ratchet member.

20. A sequence-operation counting and control device, embodying a control member, and a count ing mechanism for controlling the operation of the control member, comprising a ratchet member which with its teeth serves as the counting elements, a push rod adapted to be actuated in accordance with the variation of an external condition to be controlled, a pawl controlled by the push rod to actuate the ratchet member, a detent to normally hold the ratchet member in its advanced position, and means controlled by the push rod for rendering the detent non-efiective under certain conditions.

AUGUST J. MOTTLAU.

Lee 

